Publish Store5 Migration Guide

[matt-ramotar]

What we hit at Dropbox

• Store-rx2 only has bindings for Store4. We are considering adding Rx support to Store5: #531. We are not sure we want to commit to supporting Rx "forever". Right now folks need to add their own Rx support
• StoreRequest renamed to StoreReadRequest
• StoreResponse renamed to StoreReadResponse
• StoreBuilder modified to also take a Network generic parameter. We added a Network generic parameter with the introduction of Converter. Because Store4 had no concept of conversion, for every existing usage, Network generic is equal to Output generic
• clearAll renamed to clear
• Store library moved from Dropbox to MobileNativeFoundation

[digitalbuddha]

I'm going to split out a converting builder to undo the breaking change with store4 builder

[laurenyew-nytimes]

+1 would like a migration guide.

[inktomi]

The docs should include a mapping for the new package names as well.